1. Field of the Invention
The present invention relates to remote procedure call clients, and more particularly to a method of communicating asynchronous events from a server to remote procedure call clients.
2. Description of the Related Art
Computer systems for distributed and remote applications are increasingly being designed for a client-server model and a RPC (Remote Procedure Call) model. In a client-server model, front-end clients present information to a user, and a back-end server performs computing task for the clients. A client usually manages a user interface, and the server usually handles data storage, queries, and manipulation. A client-server model enhances efficiency by allowing resources to be shared among numerous computers and provides ease of network administration. A client-server model is understood to encompass the growing computing needs that extend from corporate desktop PCs to corporate computing levels.
A client and a server each have their own address space. A RPC model, an industry standard which includes a server and a remote procedure client, makes it appear to users as though a client directly calls a procedure located in a remote server program. For example, instead of containing the actual code that implements a remote procedure, client stub code within a client retrieves the required parameters from the client address space, translates the parameters from a local data representation to a network representation, and calls functions in a RPC client runtime library within the client to send the request and parameters to the server. A server runtime library within the server accepts the request and calls server stub code within the server. The server stub code retrieves the parameters from a network buffer, translates the parameters from the network representation to a local data representation, and calls the actual procedure on the server. The remote procedure may return its data to the server stub code. Output parameters are then returned to the server RPC runtime library by the server stub code.
To obtain asynchronous events from a server of a computer system configured for an RPC model it has been necessary for a RPC client to execute a remote procedure call to a server. A remote procedure call by a RPC client permits a RPC client to poll a server to obtain asynchronous event information. RPC client software has not provided a method for a server to communicate to a RPC client about an asynchronous event without the RPC client first polling the server.
Polling of a server by a RPC client in order to keep asynchronous event information current has caused network traffic and system overhead. Polling also allows asynchronous event information at a server to become stale for certain periods until the server is polled and the asynchronous event information is received by the RPC client. If the poll frequency is increased in an effort to maintain more current asynchronous event information from a server, then network traffic is also undesirably increased.